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Cerebellopontine Angle Tumors: Diagnosis and Management

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Cerebellopontine Angle Tumors: Diagnosis and Management

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    1. Cerebellopontine Angle Tumors: Diagnosis and Management Andrew Coughlin, MD Tomoko Makishima, MD University of Texas Medical Branch Department of Otolaryngology Grand Rounds Presentation September 30, 2010

    2. Outline History of CPA tumors Discuss Relevant Anatomy Epidemiology and Tumor Biology Signs/Symptoms of CPA tumors Brief overview of other CPA tumors Treatment options Present a case presentation

    3. Overview of CPA Tumors Represent 10% of all intracranial tumors Vestibular Schwannomas/Acoustic Neuroma represent 78% of these tumors (1) Differential Meningiomas Epidermoids Other Cranial Nerve Schwannomas Dermoid Tumors ( Chordomas, Teratomas) Arachnoid Cysts Lipomas Metastatic Tumors Vascular Tumors (Hemangioma/Glomus Tumor)

    4. History of CPA Tumors Sir Charles Balance (2,3) 1894 First successful removal of Vestibular Schwannoma 1907 Patient still alive but had CN VII paresis Harvey Cushing 1917 Monograph described CPA syndrome Pioneered subtotal resection through bilateral suboccipital craniectomy

    5. History Continued Walter Dandy (5) Advocated debulking with capsule removal and decreased operative mortality to 10% William House (6-8) Advocated Translabyrinthine approach 1960’s Introduced the microscope and dental drill to identify the facial nerve Introduced middle cranial fossa approach

    6. CPA Syndrome (4)

    7. Anatomy

    8. Epidemiology Autopsy series have shown incidence of 1.7 to 2.7% (9,10) MRI of 10,000 patients seen for non-otologic reasons showed 7 positive cases or 0.07% (11) Denmark reports of 1.3 per 100,000 population (12)

    9. Acoustic Neuroma Misnomer They are not Neuromas They rarely are found on the acoustic portion of the nerve *Involvement of the acoustic portion of the nerve often leads to erosion of the cochlea.

    10. Tumor Biology Arise from Schwann cells within the IAC (1) Equal frequency between inferior and superior divisions of the vestibular nerve. Arise from Scarpa Ganglion instead of Obersteiner-Redlich zone. Scarpa’s ganglion has highest density of schwann cells

    11. Genetics NF 2 Gene found at 22q12 Tumor suppressor gene preventing schwann cell proliferation Sporadic Variety (95%) (13) Hypothesized that there are two hits to the normal NF gene Neurofibromatosis type II Autosomal Dominant Inherit one abnormal and one normal gene with one hit to the normal allele. Blood tests available to screen family members.

    12. Biochemical Effects Neuregulin Expressed by schwann cells to control proliferation and survival of schwann cells Chemokines FGF, TGF-ß, VEGF, PDGF (14-17) Sex Hormones (18) Previous studies showed increased growth in pregnancy Recent studies have not shown growth modulation or receptors for sex hormones

    13. Workup History and Physical Exam Audiologic testing Vestibular Testing Imaging

    14. Symptoms Intracanalicular tumors Hearing Loss Tinnitus Vestibular dysfunction/Vertigo CPA extension Disequilibrium/Ataxia Brainstem Extension Midface Hypesthesia Hydrocephalus (vision loss and headache) Other Cranial Neuropathies *SNHL>tinnitus>disequilibrium>facial hypesthesia (13)

    15. Unilateral Hearing Loss Present in >85% of patients (19) 5% of patients with VS have no associated hearing loss (20) Speech discrimination out of proportion to HL Many notice difficulty on the telephone

    16. Association with SSNHL Occurs in up to 20% of patients (13) 1% of patients with SSNHL have a vestibular schwannoma (21) 48% of patients with SSNHL will have some recovery of hearing (21) Don’t rule out VS if they recover

    17. Tinnitus 2nd most common presenting sign Often precedes hearing loss Can be present without hearing loss Can be high pitch, hissing, or a roar Can localize to the opposite ear Unilateral tinnitus should be evaluated

    18. Vestibular Complaints 36-50% of patients describe disequilibrium (1) Vague, transient lightheadedness Acute vertigo is presenting symptom in 27% of patients but is associated with smaller tumors.

    19. Facial Hypesthesia Presenting symptom in 4% of patients Larger tumors >2cm Maxillary division 1st Corneal reflex is the first to go Facial weakness is rare If present should assume a different type of tumor.

    20. Ocular Complaints Rare Loss of corneal reflex Nystagmus (toward affected side) Diplopia Involvement of CN VI Blurry vision Papilledema and optic atrophy from compression

    21. Signs Hitselberger Sign Decreased sensation of EAC Sensory VII more sensitive than Motor VII Absent corneal reflex, nystagmus Hypesthesia to pinprick and touch Weakness of Temporalis/Masseter muscles Other cranial neuropathy’s Gait disturbances or difficulty with finger to nose testing

    22. Audiologic Testing Downsloping high frequency SNHL 65% (22) 5% of patients show no hearing loss (23) Rollover: Speech discrimination worse than expected and worse with increased sound intensities Retrocochlear losses more common than cochlear

    23. Hearing Classification Scales (24)

    24. Acoustic Reflexes **Positive test has 85% sensitivity for identifying retrocochlear problem Acoustic Reflex Threshold Increased (compared with cochlear norms) or absent if retrocochlear process

    25. Auditory Brainstem Evoked Response Sensitivity of 85 to 90% (25) False Positive rate 10% False Negative rate 18-30% for intracanalicular tumors Number larger than in the past Five waveforms are produced with the most common being a latency in wave V compared to the normal ear of >0.2msec. Recommended as a screening test for those with low suspicion of vestibular schwannoma.

    26. Vestibular Testing 70-90% of patients will show some abnormality (26) 50% of small tumors produce no abnormalities (27) Caloric testing is commonly the only abnormality Inferior vestibular nerve tumors may be missed Superior nerve showed decrease in 98% Inferior nerve shows decrease in only 60% (28) Therefore not used as a screening test

    27. CT Imaging 90% of vestibular schwannomas will enhance with contrast Frequently misses tumors that are not intracanalicular and do not extend >5mm to the CPA. 63% accuracy at diagnosis (29)

    28. MRI Gold Standard for Vestibular Schwannomas Can identify tumors as small as 3mm (30) Gadolinium is preferentially taken up by tumor Better visualization of small tumors Gadolinium enhanced studies Hyperintense on T1 and T2 studies Non-contrasted studies Hypointense T1, Isointense on T2 Some recommend T2 fast spin-echo MRI as screening test but most will likely require at thin slice MRI if abnormalities are found (31)

    29. MRI continued Vestibular Schwannoma Meningioma Centered on IAC Globular appearance Ice cream cone appearance in IAC Bony erosion of IAC Cystic degeneration or hemorrhage may be present Extend along petrous ridge Sessile appearance “Dural Tail” at periphery Iso/Hypointense on T1 Hypo to Hyperintense on T2

    30. Acoustic vs Meningioma

    31. Differential Diagnosis

    32. Meningiomas 3% of all CPA tumors (13) Do not metastasize but do recur due to bony invasion Are formed from cap cells around arachnoid villi near dural sinus’ and where CN’s enter their foramina Generally are not intracanalicular so must be larger to cause hearing concerns

    33. Meningioma Signs and Symptoms (32) Usually cause spontaneous nystagmus, facial hypesthesia, and gait ataxia If inferior can cause hoarseness, dysphagia, tongue atrophy If within the IAC can produce similar symptoms as Vestibular Schwannoma Hearing tests will show retrocochlear process if large enough, and 25% will have normal ABR’s (33)

    34. Meningioma Treatment Surgical Excision Must remove rim of normal dura and possibly bone Poor hearing Translabyrinthine approach Good hearing Suboccipital or Middle Fossa Approach Middle Fossa is better for more superiorly based tumors.

    35. Epidermoids Identical to cholesteatoma Develop from epithelial rest cells Slow growing Commonly don’t present until 20-30’s Arise adjacent to brainstem and infiltrate areas of least resistance Can have irregular shape and infiltrate widely

    36. Epidermoids Signs/Symptoms Facial twitching is commonly described Can become quite large before causing symptoms Progressive facial paralysis more common than schwannomas Audio/ABR/Speech discrimination consistent with other retrocochlear losses Treatment is surgical excision

    37. MRI Epidermoid (13)

    38. MRI Arachnoid Cyst (13)

    39. Facial Schwannoma Histologically identical to Vestibular Schwannomas Characteristics Rarely restricted to IAC Commonly have skip lesions Generally involve part of geniculate ganglion

    40. Facial Schwannoma Signs/Symptoms Unilateral hearing loss Tinnitus Vertigo Aural fullness (if distal to geniculate) Facial weakness is rare unless very large Hearing tests show retrocochlear process but impedance testing can show ipsilateral absent acoustic reflex

    41. Facial Schwannoma Treatment is observation If growth or facial nerve dysfunction Resection of nerve with cable grafting Translabyrinthine approach most commonly used Facial nerve decompression can be used if paresis is developing

    42. Other CPA Tumors (1) Glomus Tumors Jugular Foramen Syndrome (IX,X,XI), Surgical excision Hemangiomas Centered on geniculate, slow progressive facial weakness, surgical excision with facial nerve grafting Arachnoid Cysts Treatment is drainage Cholesterol Granulomas Bright on T1 and T2, Drained via infralabyrinthine approach Embryonic tumors (Dermoids, teratomas, chordomas) Excision with dysfunction Primary Axial Tumors of CNS (glioma, hemangioblastoma, medulloblastoma) Surgical excision +/- radiation therapy

    43. Management Observation Surgery Stereotactic Radiosurgery Radiation Therapy **Generally tumors <3cm can be treated with stereotactic radiosurgery but microsurgery is the treatment of choice

    44. Observation Growth rates vary from 0 to 2cm per year with an average of 2mm (34) 38.9-82% have some growth at =38 months (24) 14 to 24% of patients watched will go on to have some treatment (12) Age should not be determining factor Young patient with small tumor Older patient with large tumor Older patient with small tumor Single MRI is not adequate Repeat at 6 months and then again yearly Longstanding hearing loss may represent a slow growing tumor (35)

    45. Radiation Therapy

    46. Stereotactic Radiosurgery First Introduced Leskell in 1969 Gamma Knife Uses 201 ionizing beams of gamma rays from cobalt 60 source One session LINAC Uses multiple beams from a linear accelerator One session Fractionated Radiotherapy Newer therapy to eradicate cells in different cell cycle stages Multiple sessions Goal is to stop tumor growth, not shrink or remove tumor

    47. Stereotactic Radiosurgery (24) Local control = not requiring salvage therapy 87 to 100% local control rates all three combined 23% of cases have transient increase tumor volume due to central necrosis 6mo to 5yr to disappear Therefore some patients receive unnecessary salvage therapy

    48. Gamma Knife Hasegawa et al. 2005 (36) 317 patients Median follow up 7.8 years 10 yr local control >92% Partial or complete radiographic response 62% Progression free survival 96% if <15cm3 vs 57% if >15cm3 p<0.001 Better with no brainstem compression/4th ventricle obstruction p<0.001 Most tumor progression within 3 years

    49. LINAC Freidman et al. 2006 (37) 390 patients Median follow up 40 months Median dose of 12.5 Gy 5- and 10-year local control 90% Only 1% of patients required surgery for treatment failure

    50. FSRT (24) Many different regimens studied Dose 15-57.6 Gy/3-32fx Median Follow ups of 48 months 5- year local control of >90% **Relatively new idea so no long term outcomes available

    51. Radiosurgery vs FSRT (38) Tumor Control 73.8 to 100% for Radiosurgery 91.4 to 100% for FSRT Tumor Shrinkage 38 to 76.2% for Radiosurgery with single dose 34 to 76% for FSRT Tumor Growth 0-26.2% for Radiosurgery 0-12.5% for FSRT Hearing Preservation 47-71% for Radiosurgery 57-100%for FSRT

    52. Hearing Preservation Defined as G-R class I/II Early studies 16Gy = 46% Later Studies 12-13Gy = 68-78% with no change in control (24) Prasad et al. (39) 153 patients Median follow up of 4.2 years Useful hearing preservation rate of 58% Size matters <1cm3 = 75% hearing preservation >1cm3 = 57% hearing preservation

    53. Hearing Preservation GK vs FSRT Andrews et al. 2001 (40) 109 patients 63 GK at 12Gy 46 FSRT at 50Gy/25fx Follow up was 3 years 33% vs 81% hearing preservation (GK/FSRT) 98% vs 97% local control (GK/FSRT) Thought is that lower dose in multiple fractions leads to decreased late normal tissue damage

    54. Facial Neuropathy GK dose decrease from 16Gy to 12-13Gy decreased rates from 15% to 0% (41) LINAC dose decrease of 16Gy to 12.5Gy showed drop in neuropathy from 4.4% to 0.7% (37) RS vs FSRT ranges of 0-52% vs 0-4%(38)

    55. Trigeminal Neuropathy GK dose decrease from 16Gy to 12-13Gy decreased rates from 16% to 4.4% (41) LINAC dose decrease of 16Gy to 12.5Gy showed drop in neuropathy from 3.7% to 0.7% (37) RS vs FSRT ranges of 2.4-29% vs 0-16% (38)

    56. Other complications Hydrocepahlus 0-11% (24), with highest rates in FSRT Tinnitus 0.2 to 5% Ataxia 1.4 to 3.6% Vertigo 1.4 to 1.7% Peritumoral cyst formation 3.6% Malignant transformation 0 to 0.3% 3 cases in all studies reviewed with time to presentation of 5, 7.5, and 18 yrs post therapy Disequilibrium 33% likely due to weaker central compensation (42)

    57. Surgery Translabyrinthine Approach Middle Cranial Fossa Approach Retrosigmoid-Suboccipital Approach **All will require discussion/collaboration with Neurosurgery

    58. Translabyrinthine Approach (43) Advantages Disadvantages Least cerebellar retraction Wide exposure of posterior fossa No size limit for resection Facial nerve easily identified throughout Ease of facial nerve repair if damaged/resected during removal Low recurrence Low headaches Residual hearing is sacrificed Requires abdominal fat graft

    59. Middle Cranial Fossa Approach (43) Advantages Disadvantages Best hearing preservation <30db PTA >70% speech discrimination Good exposure of lateral IAC, CPA, and clivus Drilling is extradural decreasing morbidity Limited to tumors <2cm in greatest dimension Temporal lobe retraction Must dissect around facial nerve due to its superior position Limited posterior fossa exposure

    60. Retrosigmoid/Suboccipital Approach (43) Advantages Disadvantages Can attack any size tumor Hearing preservation possible Wide exposure of brainstem and lower cranial nerves Neurosurgeon familiarity Consistent facial nerve identification Must be medially located with <2cm CPA extension Lateral tumors risk injury to endolymphatic sac and vestibular labyrinth Cerebellar retraction occulomotor abnormalities and postop disequilibrium Increased air embolism risk (Sitting vs Park Bench position)

    61. Microsurgery Control Rates Translabyrinthine Total Resection 99.5 to 99.7% (44-45) Near total resection (<25mm2 or 2mm thick) Visible on MRI in 50% of patients with 3% risk of recurrence (46-47) Middle Cranial Fossa Total Resection 98% (48) Retrosigmoid Total resection 95% (49)

    62. Hearing Preservation Serviceable hearing defined as class A/B or 1/2 (24) Middle cranial fossa 51% Retrosigmoid 31% Meyer et al. 2006 (50) 162 consecutive patients via MCF approach Class A/B hearing preserved in 41% 56/113 (50%) with WR >70% preoperatively maintained that level. Tumor 0.2-1.0cm = 59% Tumor 1.1-1.4cm = 39% Tumor 1.5-2.5cm = 33%

    63. Facial Nerve Paralysis Reporting function at 6-12 month point is gold standard Preserved = Grade I/II (24) Retrosigmoid 91% Middle Cranial Fossa 88% Translabyrinthine 77% Delayed paralysis (>72hrs after surgery) Described by Grant et al. 2002 Incidence 5% (51) 79% regain postoperative function by 1 yr

    64. CSF Leak Pooled data from 19 studies 360/4297 (8%) rate (52) MCF approach 6% TL approach 8% RS approach 11% Occurs at two different time points POD 2-3 (Early) POD 10-14 (Late)

    65. Headache Occurs roughly 10% of patients >3 months postop (52) RS approach 21% MCF approach 8% TL approach 3% Mechanisms Bone dust contacting CSF/Meninges ? Aseptic Meningitis Occipital nerve entrapment Scarred neck muscles and dura Migraine

    66. Other Microsurgical Complications (53) Mortality 1% due to neurovascular injury Meningitis 1-8% Aseptic more common than bacterial (bone dust/inflammation) S. aureus most common pathogen Tinnitus 50% with preop tinnitus will have resolution postop Balance abnormalities Occurs in most patients but gone by 6-9 months Seizure/Hydrocephalus/Stroke (24) Rare and <2% of cases

    67. Microsurgery vs Radiosurgery Myrseth et al 2005 (53) Retrospective review 189 patients tumors =3cm 86 by microsurgery vs. 103 by GK 5.9 year mean follow up Local control rates of 89.2% Surgery vs 94.2% GK HB 1-2 in 79.8% Surgery vs 94.8% GK p=0.0026 Quality of life significantly lower in surgery group compared to gamma knife group *MCF approach was not utilized

    68. Microsurgery vs Radiosurgery Pollock et al. 2006 (54) Prospective cohort of 82 patients unilateral VS <3cm 36 Surgery vs 46 GK Average follow up of 42 months Local control 96% Surgery vs 100% GK p= 0.50 HB 1/2 in 75% Surgery vs 96% GK p<0.01 Hearing Preserved 5% Surgery vs 63% GK p<0.001 Quality of life all statistically better for GK Physical functioning Bodily pain scores Dizziness Handicap Inventory

    69. Summary Vestibular schwannomas are the most common CPA tumor Unilateral Tinnitus or SNHL must be evaluated Tumors <3cm in size treated with radiosurgery GK or LINAC have comparable results FSRT may prove more beneficial but requires more than 1 day of treatment For patients with no serviceable preoperative hearing, translabyrinthine approach is best choice For Hearing Preservation options the middle cranial fossa approach appears to be slightly better than the retrosigmoid approach due to decreased rates of complications.

    70. Case Report 55 y/o female with 2 year history of falls and disequilibrium Falls are now progressive and daily Denies true vertigo just imbalanced Also has tinnitus, neck spasms, and migraines She denies any hearing loss but family feels otherwise

    71. Case Report PMHx: HTN, Hypothyroidism PSHx: Partial hysterectomy and R thyroid lobectomy FHx: Noncontributory SHx: 45pack year history of smoking, -EtOH Medications: HCTZ, metoprolol, sydol prn, soma, and ambien prn Allergies: Sulfa ROS: Otherwise negative. No vision or constitutional problems

    72. Case Report General: NAD oriented x3 Head: NCAT Eyes: No nystagmus, PERRLA, EOMI ENT: TM’s intact, Tuning forks normal Neck: No masses or lymphadenopathy Neuro: CN II-XII intact, unsteady Romberg, tandem gait falling to the left, and left finger to nose ataxia

    73. Case Report Audiogram Normal hearing with mild high frequency SNHL at 4000Hz bilaterally ENG Decreased accuracy on horizontal smooth pursuit 54% weakness on left air caloric testing MRI 1.5 to 2cm lesion closely associated with CN VII/VIII. It is intracanalicular with extension into CPA. No evidence of brainstem compression or ventricular obstruction

    74. Image 1

    75. Image 2

    76. Image 3/4

    77. Treatment Plan? Finger to nose and gait ataxia Essentially normal hearing ENG positive for left lateral canal weakness 2cm tumor, no hydrocephalus

    78. Case Report Patient had previous MRI 2005 showing no tumor Therefore it is decided that we perform suboccipital craniotomy for excision of tumor

    79. Images of Surgery

    80. Images of Surgery

    81. Images of Surgery

    82. Images of Surgery

    83. Case Report Final Pathology: Meningioma No complications at this point Tuning forks 256hz and 512hz normal HB I immediately and 72 hours postoperatively

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